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991.
Dr. Sebastian Sobottka Maite Nößler Dr. Andrew L. Ostericher Dr. Gunter Hermann Noah Z. Subat Julia Beerhues Dr. Margarethe Behr-van der Meer Dr. Lisa Suntrup Dr. Uta Albold Dr. Stephan Hohloch Dr. Jean Christophe Tremblay Prof. Dr. Biprajit Sarkar 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(6):1314-1327
Asymmetric platinum donor–acceptor complexes [(pimp)Pt(Q2−)] are presented in this work, in which pimp=[(2,4,6-trimethylphenylimino)methyl]pyridine and Q2−=catecholate-type donor ligands. The properties of the complexes are evaluated as a function of the donor ligands, and correlations are drawn among electrochemical, optical, and theoretical data. Special focus has been put on the spectroelectrochemical investigation of the complexes featuring sulfonyl-substituted phenylendiamide ligands, which show redox-induced linkage isomerism upon oxidation. Time-dependent density functional theory (TD-DFT) as well as electron flux density analysis have been employed to rationalize the optical spectra of the complexes and their reactivity. Compound 1 ([(pimp)Pt(Q2−)] with Q2−=3,5-di-tert-butylcatecholate) was shown to be an efficient photosensitizer for molecular oxygen and was subsequently employed in photochemical cross-dehydrogenative coupling (CDC) reactions. The results thus display new avenues for donor–acceptor systems, including their role as photocatalysts for organic transformations, and the possibility to introduce redox-induced linkage isomerism in these compounds through the use of sulfonamide substituents on the donor ligands. 相似文献
992.
Milda Nainytė Felix Müller Giacomo Ganazzoli Chun-Yin Chan Antony Crisp Dr. Daniel Globisch Prof. Dr. Thomas Carell 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(65):14856-14860
Fossils of extinct species allow us to reconstruct the process of Darwinian evolution that led to the species diversity we see on Earth today. The origin of the first functional molecules able to undergo molecular evolution and thus eventually able to create life, are largely unknown. The most prominent idea in the field posits that biology was preceded by an era of molecular evolution, in which RNA molecules encoded information and catalysed their own replication. This RNA world concept stands against other hypotheses, that argue for example that life may have begun with catalytic peptides and primitive metabolic cycles. The question whether RNA or peptides were first is addressed by the RNA-peptide world concept, which postulates a parallel existence of both molecular species. A plausible experimental model of how such an RNA-peptide world may have looked like, however, is absent. Here we report the synthesis and physicochemical evaluation of amino acid containing adenosine bases, which are closely related to molecules that are found today in the anticodon stem-loop of tRNAs from all three kingdoms of life. We show that these adenosines lose their base pairing properties, which allow them to equip RNA with amino acids independent of the sequence context. As such we may consider them to be living molecular fossils of an extinct molecular RNA-peptide world. 相似文献
993.
Dr. Dennis Kubiczek Heinz Raber Dr. Nicholas Bodenberger Thomas Oswald Melis Sahan Daniel Mayer Dr. Sebastian Wiese Prof. Dr. Steffen Stenger Prof. Dr. Tanja Weil Dr. Frank Rosenau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(64):14536-14545
Textbook procedures require the use of individual aptamers enriched in SELEX libraries which are subsequently chemically synthesized after their biochemical characterization. Here we show that this reduction of the available sequence space of large libraries and thus the diversity of binding molecules reduces the labelling efficiency and fidelity of selected single aptamers towards different strains of the human pathogen Pseudomonas aeruginosa compared to a polyclonal aptamer library enriched by a whole-cell-SELEX involving fluorescent aptamers. The library outperformed single aptamers in reliable and specific targeting of different clinically relevant strains, allowed to inhibit virulence associated cellular functions and identification of bound cell surface targets by aptamer based affinity purification and mass spectrometry. The stunning ease of this FluCell-SELEX and the convincing performance of the P. aeruginosa specific library may pave the way towards generally new and efficient diagnostic techniques based on polyclonal aptamer libraries not only in clinical microbiology. 相似文献
994.
Dr. Florian Rauch Peter Endres Dr. Alexandra Friedrich Dr. Daniel Sieh Dr. Martin Hähnel Dr. Ivo Krummenacher Prof. Dr. Holger Braunschweig Prof. Dr. Maik Finze Prof. Dr. Lei Ji Prof. Dr. Todd B. Marder 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(57):12951-12963
Using a new divergent approach, conjugated triarylborane dendrimers were synthesized up to the 2nd generation. The synthetic strategy consists of three steps: 1) functionalization, via iridium catalyzed C−H borylation; 2) activation, via fluorination of the generated boronate ester with K[HF2] or [N(nBu4)][HF2]; and 3) expansion, via reaction of the trifluoroborate salts with aryl Grignard reagents. The concept was also shown to be viable for a convergent approach. All but one of the conjugated borane dendrimers exhibit multiple, distinct and reversible reduction potentials, making them potentially interesting materials for applications in molecular accumulators. Based on their photophysical properties, the 1st generation dendrimers exhibit good conjugation over the whole system. However, the conjugation does not increase further upon expansion to the 2nd generation, but the molar extinction coefficients increase linearly with the number of triarylborane subunits, suggesting a potential application as photonic antennas. 相似文献
995.
Stepan Geri Tereza Krunclova Dr. Olga Janouskova Dr. Jiri Panek Dr. Martin Hruby Daniel Hernández-Valdés Dr. Benjamin Probst Prof. Roger A. Alberto Dr. Constantin Mamat Dr. Manja Kubeil Dr. Holger Stephan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(48):10992-11006
Two photoactivatable dicarbonyl ruthenium(II) complexes based on an amide-functionalised bipyridine scaffold (4-position) equipped with an alkyne functionality or a green-fluorescent BODIPY (boron-dipyrromethene) dye have been prepared and used to investigate their light-induced decarbonylation. UV/Vis, FTIR and 13C NMR spectroscopies as well as gas chromatography and multivariate curve resolution alternating least-squares analysis (MCR-ALS) were used to elucidate the mechanism of the decarbonylation process. Release of the first CO molecule occurs very quickly, while release of the second CO molecule proceeds more slowly. In vitro studies using two cell lines A431 (human squamous carcinoma) and HEK293 (human embryonic kidney cells) have been carried out in order to characterise the anti-proliferative and anti-apoptotic activities. The BODIPY-labelled compound allows for monitoring the cellular uptake, showing fast internalisation kinetics and accumulation at the endoplasmic reticulum and mitochondria. 相似文献
996.
The linear density-density response function represents a formulation of the generalized density response of a molecular (or extended) system to arbitrary perturbing potentials. We have recently established an approach for reducing the dimension of the (in principle infinite) eigenspace representation (the moment expansion) and generalized it to arbitrary self-adjoint, positive-definite, and compact linear operators. Here, we present a modified representation—the reduced eigensystem representation—which allows to define a trivial criterion for the convergence of the approximation to the density response. By means of this novel eigensystem-like structure, the remarkable reduction of the dimensionality becomes apparent for the calculation of the density-density response function. 相似文献
997.
Juri Skotnitzki Alexander Kremsmair Daniel Keefer Ye Gong Regina de Vivie‐Riedle Paul Knochel 《Angewandte Chemie (International ed. in English)》2020,59(1):320-324
We report palladium‐catalyzed cross‐coupling reactions of chiral secondary non‐stabilized dialkylzinc reagents, prepared from readily available chiral secondary alkyl iodides, with alkenyl and aryl halides. This method provides α‐chiral alkenes and arenes with very high retention of configuration (dr up to 98:2) and satisfactory overall yields (up to 76 % for 3 reaction steps). The configurational stability of these chiral non‐stabilized dialkylzinc reagents was determined and exceeded several hours at 25 °C. DFT calculations were performed to rationalize the stereoretention during the catalytic cycle. Furthermore, the cross‐coupling reaction was applied in an efficient total synthesis of the sesquiterpenes (S)‐ and (R)‐curcumene with control of the absolute stereochemistry. 相似文献
998.
Shengdong Wang Rgis Guillot Jean‐Franois Carpentier Yann Sarazin Christophe Bour Vincent Gandon David Lebuf 《Angewandte Chemie (International ed. in English)》2020,59(3):1134-1138
Herein, we report the preparation of bridged tetrahydrobenzo[b]azepines, which was accomplished through an aza‐Piancatelli cyclization/Michael addition sequence in a one‐pot fashion from readily available precursors. It is noteworthy that a general method to access these scaffolds was hitherto unprecedented. Additionally, the multifaceted aspects of this process have been exemplified through its application to the synthesis of 2‐azabicyclo[3.2.1]octanes and bridged tetrahydrobenzo[b]oxepines, along with post‐derivatizations. 相似文献
999.
Manuel G. Ricardo Ameena M. Ali Jacek Plewka Ewa Surmiak Beata Labuzek Constantinos G. Neochoritis Jack Atmaj Lukasz Skalniak Ran Zhang Tad A. Holak Matthew Groves Daniel G. Rivera Alexander Dmling 《Angewandte Chemie (International ed. in English)》2020,59(13):5235-5241
Stapled peptides are chemical entities in‐between biologics and small molecules, which have proven to be the solution to high affinity protein–protein interaction antagonism, while keeping control over pharmacological performance such as stability and membrane penetration. We demonstrate that the multicomponent reaction‐based stapling is an effective strategy for the development of α‐helical peptides with highly potent dual antagonistic action of MDM2 and MDMX binding p53. Such a potent inhibitory activity of p53‐MDM2/X interactions was assessed by fluorescence polarization, microscale thermophoresis, and 2D NMR, while several cocrystal structures with MDM2 were obtained. This MCR stapling protocol proved efficient and versatile in terms of diversity generation at the staple, as evidenced by the incorporation of both exo‐ and endo‐cyclic hydrophobic moieties at the side chain cross‐linkers. The interaction of the Ugi‐staple fragments with the target protein was demonstrated by crystallography. 相似文献
1000.
Huiyun Jiang Yameng Ren Weiwei Zhang Yongzhen Wu Etienne Christophe Socie Brian Irving Carlsen Jacques‐E. Moser He Tian Shaik Mohammed Zakeeruddin Wei‐Hong Zhu Michael Grtzel 《Angewandte Chemie (International ed. in English)》2020,59(24):9324-9329
Dye‐sensitized solar cells (DSSCs) based on CuII/I bipyridyl or phenanthroline complexes as redox shuttles have achieved very high open‐circuit voltages (VOC, more than 1 V). However, their short‐circuit photocurrent density (JSC) has remained modest. Increasing the JSC is expected to extend the spectral response of sensitizers to the red or NIR region while maintaining efficient electron injection in the mesoscopic TiO2 film and fast regeneration by the CuI complex. Herein, we report two new D‐A‐π‐A‐featured sensitizers termed HY63 and HY64 , which employ benzothiadiazole (BT) or phenanthrene‐fused‐quinoxaline (PFQ), respectively, as the auxiliary electron‐withdrawing acceptor moiety. Despite their very similar energy levels and absorption onsets, HY64 ‐based DSSCs outperform their HY63 counterparts, achieving a power conversion efficiency (PCE) of 12.5 %. PFQ is superior to BT in reducing charge recombination resulting in the near‐quantitative collection of photogenerated charge carriers. 相似文献